Control mechanism for hydraulic pumps



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CONTROL IBCHANISI FOR HYDRAULIC PUMPS Filed Dec 26, 1942 INVENTOR WALTER ERNST,

ATTORNEY Patented Dec. 4, 1945 umrgo STATES PATENT OFFICE oou'mor. mncna ii gti roa 'nrnnaumc Walter Ernst, Mount Gilead, Ohio, assignor to The Hydraulic Development Corp. Ina, Wile mington, Del, a corporation of Delaware Application December 26, 1942, Serial No. 470,136 x e Claims. (01. 103-38) indirectly through a servomotor. Gne end or the lever is usually connected to an eiectromagnet or a hydraulic thruster. The other and terminates vide improved structure by which the slamming effect between the lever knob and the push rod is avoided. This object is attained in brief by providing a yielding connection between the pivoted lever and the pump control linkage which will permit the rod on the lever to maintain a steady contact with the push rod even when the platen moves through a considerable distance. There can therefore be no sudden impact between the push rod and; the pivoted lever when the platen is returning to its initial position. i

of Figure I but in a diflerent operating position. Figure 3 is a plan view, somewhat enlarged, of

n the. support on which the lever and certain parts The invention will be better understood when reference is made to the following specification and the accompanying drawing in which: 7

Figure 1 is a diagrammatic view of a variable delivery Pump and an associated press together with-the" necessary levers and linkage for controlling the output of the pump to the press.

Figure 2 is a diagrammatic fragmentary view of the control lever and linkage shown at the left of the linkage are mounted. This view is taken at the approximate pqsition designated by the line 3-3 in Figure 1. V

Figure 4 is a sectional view taken along line 4-4 in Figure 3.

Referring to the drawing, reference numeral in a knob which is adapted to be struck by the I designates a variable delivery pump having a push rod of the platen when the latter is retumpair of oppositely extending casings 2, 3 one of ing to its initial position. The linkage rods for which includes a reciprocatory mechanism for actuating the shift ring and which are under the reversing the hydraulic connections of the pump control of the electromagnet or thruster are conand the other casing contains a self-centering nected between the pivoted lever and the control spring mechanism. The ingress and egress openelement of the hydraulic pump. ings of the pump arebrought out through a large The pivoted lever and the linkage rods are casing 4 having ports 5, 6 which may constitute usually keyed. or otherwise secured together so alternate inlet and discharge ports depending on that the movement of the lever is limited by the the position of the valve controlling mechanism movement of the control linkage. t the beginwithin the casing 2. Conduits i, 8 are taken rening of the downward stroke, the lever is moved spectively from opposite sides of the pump to a upwardly about its pivot away from the push r d. press cylinder 9, the upper end of which enters As the stroke proceeds the push rod moves downan oil reservoir 10. The cylinder contains a piswardly with the platen and thus increases the ton (not shown) having a piston rod II which distance between the lever and push rod. 0n the extends downwardly from the cylinder and terretum stroke, the lever will reverse and back inmates in a plat n The conduits 3 enter down, striking the push rod with a heavy impact the cylinder 9 on opposite sides of the piston as which introduces jar into the various parts and is well known in the art. The reservoir tank l0 may on occasion, fracture the lever. may include the usual form of surge valve and The primary object of the invention is to pro- 0 other control devices, valves, etc., by which fluid is introduced into either end of the cylinder 9 and withdrawn from the opposite end as is well known in the art.

A rod or bar I3 is taken from the platen l2 and is provided at the end with an opening for slldably receiving a push rod H. The latter is mounted in a guideway l5 and is provided at the upper end with a hardened shoulder portion it. A slidable collar I! is carried by the rod l4, and is adapted to be fixedly secured to the rod by a screw IS.

A system of levers and linkage generally indicated at I! is provided for controlling the mechanism within the casing 2. The mechanism I! may comprise a lever 20 which is pivoted at its middle 2| on a, support 22. The right hand end of the lever is swivelly connected to a rod and a lever 24 which carries a control rod 25 reciprocably mounted in the casing 2. A pivoted casing. The rod 23 is connected either with a servo-valve within the casing 2 or directly to a shift ring which controls the direction of movement ofthe pressure fluid delivered by the pump I.

. The left hand end of the lever 23 is swivelly connected to a downwardly depending rod 21 which carries a plunger 23 forming the actuated 23. A tension spring 33 may be connected between the left hand end of the lever 23 and a support 3|. The arrangement is such that when the plunger 23 is caused to move downwardly the rod 23 moves upwardly to cause the rod 25 to shift to the right and to place the pump on stroke. 23 is de-energized or rendered inoperative the spring 33 will cause the lever 23 to move clock- 'wise, thereby withdrawing the rod 23. The shift The lever 33 is provided with 'a circular hub 35 which serves to space the lever from the wall or support 32. At a position remote from the hub 33, the lever is provided with a pair of oppositely disposed segmental portions 33 of circular configuration and spaced'fror'n one another. These portions extend toward the lever 23. The latter is also provided with similarly shaped segments 33 which extend toward the lever 33. These segments 33 mesh with the segments 33 of the lever 33. In order to permit this meshing effect, suitable counterbored recesses are provided in the hubs of the respective levers as can be seen in On the other hand, when the device element of an electromagnetic device or thrustor push rod moves downwardly the lever 33 is permitted to follow the movement of the push rod so that the knob 34 continues to make contact with the collar It. This condition is shown in Figure 2.

At the end of the work stroke any suitable apparatus may be employed to de-energize the device 23, for example a tonnage valve (not shown) which responds to excess back pressure above the piston in the cylinder 3. This valve when operated may open an electrical circuit through a limit switch which in turn controls the electromagnetic device 23. When the latter is de-energized the spring 33 immediately draws the plunger 23 upwardly causing the lever 23 to rotate clockwise and to withdraw the control rod 23 from the casing 2. Thus the shift ring in the pump is moved through its neutral position. to its other extreme on-stroke position whereby the pump discharge is reversed. Pressure fluid is now admitted to the conduit 3 and withdrawn from the conduit 1 to force the piston in the cylinder 3 upwardly.

It is apparent that when the lever 33 was moved clockwise during the downward motion of the platen the spaces 33 between the adjacent segments 33; 33 were moved from the position shown in Figure 4 to the position indicated at 42. Consequently, when the lever 23 is caused to move clockwise u on de-energization of the device 23 there is sufficient space at the positions 42 to accommodate a clockwise movement of the segments 33. During the return stroke of the platen the bar l3 moves upwardly and when the bar reaches the adjustable collar H the push rod is moved in a vertical direction, causing the lever :13 to move counterclockwiseto its initialposi- During this movement the left hand face of the upper segment 33 (Figure 4) and the right hand face of the lower segment 33 are main- Figure 3. The segments 33 have an inner periphery which loosely fits about the shaft 2| and are also provided with flat end surfaces. The width of the segments 33 is considerably less than the space on each side of the segments 33 so that in their mesh ng relationthere is a wedge shaped space 33 between the two pairs of adjacent segments.

The levers 23. 33 are maintained in their. proper position along the shaft 2| by means of a nut or screw collar 43 and if desired a washer 3| may be inserted between the collar and the outer surface 23.

Operation of the mechanism Assume that the device 23 has been energized or actuated, the lever 23 will be caused to rotate caused to move to the right, to place the pump.

on stroke. Pressure fluid is supplied by the pump to conduit I and withdrawn from the conduit 3,

tained in contact with the adjacent surfaces of the segments 33 so that an upward movement of the lever 33 causes the segments 33 to be rotated counterclockwise which in eflect causes the lever 23 to be moved from the reverse on-stroke position to a horizontal neutral position. The rod 25 is therefore moved inwardly of the casing 2 to a position intermediate of its forward and reverse on-stroke positions and the shift ring is brought to its neutral position. Under these circmnstances the output of the pump is effectively cut off so that the piston in the cylinder 3 comes to rest at its uppermost position and poised ready to be driven downwardly when the device 23 is again actuated in any suitable and well known manner.

It is apparent .that regardless of the instantaneous position of the push rod M. the lever 33 forcing the piston in the cylinder 3 to move downwardly and to carry the platen in the same direction. As the platen moves downwardly, the bar |3 also moves throughthe same distance permitting the push rod N to descend. It has been pointed out that the spaces 33 were notcompletely closed by .the rotation of the segments 33 so that a sufliclent space is left for the segments 33 to rotate clockwise. Thus, as the maintains a continuous contact with the rod and there is no slamming effect between the collar l3 and the knob 34. Prior to the present invention, the levers 33 and 23 were keyed to the shaft 2| so that a counter-clockwise movement of the lever 23 would normally draw the knob 34 upwardly away fromthe collar and the distance would be increased as the push rod moves downwardly during the work stroke. 'When the platen was ready to return and the lever 23 was rotated clockwise, the lever 33 would normally back down and strike the collar 33. All of thistended to subject the partsincluding the shaft 2|, linkages 23, 24 and the control rod 23 as well as the levers 23 and 33 to extreme Jar and shock which on occasion might be suflicient to break one or moreoi these parts depending on the distance that the platen had moved and the speed with which it was retracted.

However, by providing a yielding clutch or jaw,

mechanism obtained through the segments 33, 33 which permits the lever 33 to move clockwise when the lever has been moved counterclockwise (Figure 2) the lever 33 is enabled to maintain a continuous contact with the push rod I 4 and re ardless of the position of the lever 20 so as to eliminate any impact or slamming proportions with the push rod. It is apparent that the width oi the segments 33. 33 may be predetermined to provide the spacings 39 of proper width so as to permit the lever 23 to be rotated counter-clockwise and the lever 33 to be rotated clockwise and assume the respective positions shown in Figure 2. It is further evident that the presence of the spacin s 33. when positioned as shown in Figure 4 or-when the spacings have been efiectively moved to the positions 42 cannot prevent the lever ,33 from restoring the lever 23 to its horizontal or neutral position her use at this time, the segments 33 are already in contact with the se ments 33 and a counter-clockwise segmental members, one pair of members being secured to the other of said levers, said members being arranged about said shaft and having a width such as to provide spaces between the two pairs or the segmental members whereby one lever is adapted to move through a limited distance with respect to the other lever, and means for resiliently maintaining the parts of said levers in contact with each other prior to and during their'movement in one direction.

3. In apparatus for controlling the operation of a pressure fluid pump, a push rod for shifting the control element of the pump to its neutral position, a pair of levers mounted on a shaft.

one of said levers serving to control the on-stroke positions of the pump and the other lever serving to control the neutral position of the pump,

1 said levers being connected togethe through a lost modpn coupling which permits said other lever to maintain a continuous contact with said push rod said coupling comprising interengaging segments on said levers at the position 01 said shaft, and means for resiliently maintaining the parts of said levers in contact with each other movement of se ments 33 will obviously rotate .the segments 33 through a corresponding angle prior to and during their movement in one direction.

4. In a control for a reversible delivery pump having a control element shii'table from a first position effecting full pump delivery in one direction, through neutral, to a. second position effecting full pump delivery in the opposite direction, a shaft, a first double arm lever pivoted upon said shaft, a linkage connecting one end of said lever to said element, resilient means act-w ing on the second end 01' said lever to thereby move said element into said first position, a power device connected to said second end of the lever to move said element into said second position against the action of said resilient means.

40 a push rod, a second lever pivoted on said shalt Havin thus fully described my invent on.

what I claim as new and desire to secure by Letters Patent is:

1. Ap arat s for controlling the operation of a p essure fluid pum said apparatus including a pair of levers rotatably mounted on a shaft, one end of one oi said levers being pivotally connected to an actuating element and the other and having its end continuously in contact with saidrod for actuation thereby, and a lost motion connection between said levers whereby said end of said one level being connected to the control rod of the pump. the second of said pair of levers being connected to the first of said air oi levers throu h a lost motion couplin which in contact with each other prior to and during v their movement in one direction.

second lever operates said first lever only from first position to neutral on corresponding motion of said push rod.

5. In a control for a reversible delivery pump having a control element shiftable between a first position effecting i'ull delivery in one direction of flow and a second position eflfecting full delivery in the other direction of fiqw, a first lever pivoted intermediate its ends, a linkage operatively connecting one end of said lever with said element for so shifting said element, resilient means connected to urge said lever and element into said first position, a p wer device operable on the other end of said lever to move the action of said resilient means. .a push rod, a

second lever pivoted adjacent said-first lever and having a portion in continuous engagement with said push rod to be actuated by movement 2. Apparatus for controlling the operation of a pressure fluid pum said apparatus including a pair of levers rotatably mounted on a shaft, one end of one of said levers being pivotally connected to an actuating element and the other end of said lever being connected to the control rod of the pump.-the second of said pair of levers being connected to the first of said air 01' levers through a lost motion coupling which permits the second lever to move in a direction opposite to the direction in which the first lever is moved by said actuating element, said coupling including two pairs 01' oppositely disposed thereof, and a lost motion connection between said levers for effecting motion of said first lever by said second lever, from first position to neutral only, on corresponding movement or said push rod.

6. In a control system for a reversible pump having a control element movable from. a first position eifectlng lull pump delivery in one direction of fiow, through neutral, to a second position effecting full pump delivery in the opposite direction of fiow, a pivoted two-armed lever having one end connected to operate said element and having pivoted positions correspond- 4 i I I 2390300 ing to the said positions of said element, means connected to the second end of said lever ur ing'the same into said first position, a power device connected to the second end of said lever operable to move said lever and element into said second position against the action 01' said urging means, a push rod adapted to be actuated by a device driven by the delivery of said pump, a second lever pivoted coaxially with and adjacent said first lever and in continuous contact with said push rod for pivoting thereby, and a lost motion connection between said levers,

I said connection comprising segments coaxially tuation of said push rod.

WALTER ERNST. 

